Light-emitting device and display device

ABSTRACT

Although an organic resin substrate is highly effective at reducing the weight and improving the shock resistance of a display device, it is required to improve the moisture resistance of the organic resin substrate for the sake of maintaining the reliability of an EL element. Hard carbon films are formed to cover a surface of the organic resin substrate and outer surfaces of a sealing member. Typically, DLC (Diamond like Carbon) films are used as the carbon films. The DLC films have a construction where carbon atoms are bonded into an SP 3  bond in terms of a short-distance order, although the films have an amorphous construction from a macroscopic viewpoint. The DLC films contain 95 to 70 atomic % carbon and 5 to 30 atomic % hydrogen, so that the DLC films are very hard and minute and have a superior gas barrier property and insulation performance.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a device (hereinafter referredto as a light-emitting device) that has an element (hereinafter referredto as a light-emitting element) where a thin film including aluminescent material is sandwiched between a pair of an anode electrodeand a cathode electrode. In particular, the present invention relates toa light-emitting device whose light-emitting element includes a thinfilm (hereinafter referred to as a light-emitting layer) made of anelectro-luminescent material (EL material). The present invention alsorelates to a display device that uses a substrate made of an organicresin material and, more particularly, to a display device where a pixelportion is formed on such a substrate using thin-film transistors and anEL material.

[0003] 2. Description of the Related Art

[0004] Liquid crystal panels or EL materials applied to display devicesmay contribute to reduction in weight and thickness thereof incomparison with conventional CRTs. Therefore, attempts have beenrecently made to apply display devices using the liquid crystal panelsor EL materials to various fields. Also, it has now become possible toconnect portable telephones and personal digital assistants (PDAs) tothe Internet, which leads to the dramatic increase in the amount ofimage information to be displayed thereon and creates increasing demandfor high-definition color display devices.

[0005] Display devices used for such portable information terminals needto be reduced in weight and, for instance, portable telephones whoseweights are below 70 g are now on the market. For the reduction inweight, almost all components, such as electronic components, housing,and batteries, of the portable information terminals are subjected toreengineering. For the further weight reduction, however, displaydevices need to be reduced in weight.

[0006] Display devices are produced using glass substrates in manycases, so that one conceivable method for weight reduction would be toreduce the thickness of the glass substrates. In this case, however, theglass substrates tend to be cracked and the shock resistance thereof islowered. This becomes a serious hindrance to the application of displaydevices including such thin glass substrates to portable informationterminals. To meet demand for weight reduction as well as shockresistance, the development of display devices using organic resinsubstrates (plastic substrates) is under consideration.

[0007] For instance, light-emitting devices that have light-emittingelements produced using EL materials are currently under development.Display devices whose pixel portions are formed using light-emittingelements are capable of emitting light by themselves and further do notrequire light sources, such as backlights, unlike liquid crystal displaydevices. As a result, such light-emitting elements are highly expectedas an effective means for reducing weights as well as thickness ofdisplay devices.

[0008] The construction of a typical light-emitting element using anorganic EL material is shown in FIG. 22. In this drawing, an insulator2201, an anode 2202, a light-emitting layer 2203, and a cathode 2204 arelaminated to form a light-emitting element 2200.

[0009] Before being observed by an observer 2206, light 2205 emittedfrom the light-emitting layer directly passes through the anode 2202, oris reflected by the cathode 2204 and then passes through the anode 2202.That is, the observer 2206 observes the light 2205 that and passesthrough the anode 2202 to be emitted in picture elements where thelight-emitting layer 2203 performs light emission.

[0010] A light-emitting element is composed of two electrodes: an anodethat injects holes into an organic compound layer including alight-emitting layer, and a cathode that injects electrons into theorganic compound layer. The light-emitting element having thisconstruction utilizes a phenomenon where light is emitted when the holesinjected from the anode are recombined with the electrons injected fromthe cathode within the light-emitting layer. The organic compound layerincluding the light-emitting layer is degraded by various factors, suchas heat, light, moisture, and oxygen. To prevent this degradation, anordinary active matrix type light-emitting device is produced by forminglight-emitting elements in a pixel portion after wiring andsemiconductor elements are formed therein.

[0011] After the formation of the light-emitting element, a firstsubstrate, on which the light-emitting element have been formed, and asecond substrate for covering the light-emitting elements are laminatedand sealed (packaged) using a sealing member. This construction preventsthe light-emitting elements from being exposed to the outside air.

[0012] It should be noted here that in this specification, all layersprovided between a cathode and an anode are collectively referred to asan organic compound layer. The organic compound layer has a well-knownstructure where, for instance, a hole injecting layer, a light-emittinglayer, an electron transporting layer, and an electron injecting layerare laminated with each other. A predetermined voltage is applied to theorganic compound layer by a pair of electrodes to cause therecombination of carriers, thereby causing light emission in thelight-emitting layer.

[0013] The light-emitting element, however, has a problem as todurability and, in particular, to oxidation resistance. The cathode thatinjects electrons into the organic compound layer is ordinarily made ofan alkaline metal or an alkaline earth metal having a low work function.It is well known that these metals tend to react with and water, therebyhaving low oxidation resistance. The oxidation of the cathode means thatthe material of the cathode loses electrons and is coated with anoxidation layer. The reduction in the number of electrons to be injectedand the oxidation coat may reduce the amount of emitted light inbrightness.

[0014] As described above, the electrode of the light-emitting elementis easily oxidized with a considerably small amount of oxygen ormoisture and therefore the light-emitting element is easily degraded.Various techniques have been developed to prevent the oxidation of thelight-emitting element. For instance, the light-emitting element issealed with a metal or glass that is impermeable to oxygen and moisture.Also, the light-emitting element is produced to have a resin laminationconstruction or is filled with nitrogen or an inert gas. Even if thelight-emitting element is sealed with a metal or a resin, however,oxygen easily passes through small gaps and oxidizes the cathode andlight-emitting layer. Also, moisture easily passes through the resinused to seal the light-emitting element in terms of the light-emittingelement. This causes a problem in that areas (called dark spots) that donot emit light appear on a display screen and expand with the lapse oftime, which makes the light-emitting element incapable of emittinglight.

[0015] EL materials are capable of emitting blue light and thus it ispossible to realize a full-color display device of a self-light emittingtype with the materials. However, it is confirmed that organiclight-emitting elements are degraded in various ways. This degradationprevents the actual use of the EL materials and a solution to thisproblem is urgently required. The dark spots are spot-shaped defectsthat do not emit light in the pixel portion and so degrade displayquality. The dark spots are also defects that get worse over time. Evenif the light-emitting element is not brought into operation, the numberof the dark spots is increased by the existence of moisture. It isthought that the cause of the dark spots is the oxidation reaction ofthe cathode made of an alkaline metal. To prevent the occurrence of darkspots, a sealed space is filled with dryer gas or provided with a dryeragent, in which the light-emitting element is placed.

[0016] Also, the light-emitting element is vulnerable to heat thatpromotes oxidation. This means that there are many factors causingoxidation and therefore it is difficult to make actual use oflight-emitting devices. In view of the problems described above, theobject of the present invention is to provide a light-emitting devicewith a high degree of reliability and an electronic device where ahigh-reliability display unit is achieved using such a light-emittingdevice.

[0017] It is well known that a substrate made of an organic resinmaterial has high permeability to moisture, in comparison with a glasssubstrate. For instance, the permeability to moisture of polyether imideis 36.5 g/m²·24 hr, that of polyimide is 32.7 g/m²·24 hr, and that ofpolyether terephthalate (PET) is 12.1 g/m²·24 hr.

[0018] As is apparent from this, if a display device produced with alight-emitting element including an organic resin substrate is leftstanding in the air for a long time period, moisture gradually permeatesand the organic light-emitting element is degraded. In addition, asealing member used to seal a light-emitting element is also made of anorganic resin material, so that it is difficult to completely preventoxygen and moisture in the air from entering through sealed portions.

[0019] Also, an organic resin substrate is soft, in comparison with ametal substrate or a glass substrate, so that scratches or the like areeasily made thereon. Further, the long-term exposure to the directsunlight causes a light chemical reaction and alters the quality andcolor of the organic resin substrate.

[0020] As described above, the organic resin substrate is a highlyeffective means to realize a display device reduced in weight with highshock resistance, although there remain many problems that must besolved in order to ensure the reliability of the light-emitting element.In view of these problems, the object of the present invention is toprovide a display device that uses a light-emitting element with a highdegree of reliability.

[0021] Also, if the outside light (the light existing outside thelight-emitting device) enters picture elements that do not emit light,the light is reflected by the back surface (the surface contacting theorganic compound layer) of the cathode, so that the cathode back surfacefunctions as a mirror and reflects the outside scenes. To solve thisproblem, a circular polarizing film has conventionally been applied to alight-emitting device to prevent the reflection of the outside scenestoward the observer, although this construction raises the fabricationcost because the circular polarizing film is high-priced. In view ofthis problem, the object of the present invention is to prevent thismirror reflection phenomenon of a light-emitting device without using acircular polarizing film.

SUMMARY OF THE INVENTION

[0022] According to the present invention, in a display device using anorganic resin substrate, a hard carbon film is formed on a surface ofthe substrate as a protecting film that prevents from entering moistureor the like and the scratches on the surface. In particular, a DLC(Diamond like Carbon) film is used with the present invention. The DLCfilm has a construction where carbon atoms are bonded into a diamondbond (Sp³ bond) in terms of a short-distance order, although the filmhas an amorphous construction containing a graphite bond (Sp² bond) froma macroscopic viewpoint. The DLC film contains 95 to 70 atomic % carbonand 5 to 30 atomic % hydrogen, so that the DLC film is very hard andexcels in insulation. The DLC film is also characterized by low gaspermeability to moisture and oxygen. Further, it is known that thehardness of the DLC film is 15 to 25 Gpa in the case of measurementusing a micro-hardness meter.

[0023] The DLC film is formed using a plasma CVD method, a microwave CVDmethod, an electron cyclotron resonance (ECR) CVD method, or asputtering method. With any of these methods, the DLC film is formed inintimate contact without heating the organic resin substrate. The DLCfilm is formed under a situation where the substrate is set on acathode. Alternatively, the DLC film is formed by applying a negativebias and utilizing ion bombardment to some extent. In the latter case,the DLC film becomes minute and hard.

[0024] The reaction gas used to form the DLC film is hydrocarbon gas,such as CH₄, C₂H₂, and C₆H₆. The DLC film is formed by ionizing thereaction gas by means of glow discharge and bombarding a cathode, towhich a negative self-bias is applied, with accelerated ions. In thismanner, the DLC film becomes minute and flat. The DLC film may be formedwithout heating the substrate to a high temperature, so that theformation of the DLC film can be performed in the final manufacturingstep where a display device is finished.

[0025] By forming the DLC film on at least one surface of the organicresin substrate, the gas barrier property is improved. Alternatively,the gas barrier property is improved by forming the DLC film on theouter surface of a sealing member used to laminate an organic resinsubstrate (hereinafter, an element substrate), on which TFTs andlight-emitting elements are formed, with a sealing substrate for sealingthe light-emitting elements. In this case, the thickness of the DLC filmis in a range of 5 nm to 500 nm. Also, by forming the DLC film on alight incident surface, ultraviolet rays are blocked, the light chemicalreaction of the organic resin substrate is suppressed, and thedegradation of the organic resin substrate is prevented.

[0026] The DLC film that prevents oxygen and moisture from entering isformed to successively cover exposed portions of the sealing member andside portions of the first and second substrates that are laminated toproduce the light-emitting device. The exposed portions of the sealingmember and the side portions of the first and second substrates arehereinafter collectively referred to as “end surfaces”. With aconventional technique, oxygen and moisture pass through a resinprovided at end portions. The construction described above, however,prevents moisture from entering through between the first and secondsubstrates.

[0027] A dryer agent is provided in a space between the elementsubstrate and the sealing substrate sealed by the sealing member,thereby suppressing the degradation of the light-emitting elements. Forinstance, a barium oxide can be used as the dryer agent. The dryer agentis provided at positions (for instance, on a driving circuit, on apartition wall, or within the partition wall) outside light-emittingareas. With this construction, the dryer agent absorbs gas and moisturecontained in the light-emitting elements as well as oxygen and moisturepassing through a sealing resin in the end portions. As a result, thedegradation of the light-emitting elements is prevented. Further, byforming an organic interlayer insulating film using a black resin, themirror reflection phenomenon (the reflection of the outside scenes) ofthe light-emitting device is prevented. Also, the black resin may beused in an area in which the sealing member is formed.

[0028] The DLC film described above is applicable to passive typedisplay devices as well as active matrix type display devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the accompanying drawings:

[0030]FIGS. 1A to 1D each show a position where DLC film is formed on anorganic resin substrate according to the present invention;

[0031]FIG. 2 shows the construction of a plasma CVD apparatus used toform DLC films used in the present invention;

[0032]FIGS. 3A and 3B each show the construction of the reaction chamberof the plasma CVD apparatus;

[0033]FIG. 4 is a cross to sectional view showing the constructions ofthe driving circuit and pixel portion of a display device;

[0034]FIGS. 5A and 5B are respectively a top view and an equivalentcircuit diagram showing the construction of the pixel portion of thedisplay device;

[0035]FIG. 6 is a perspective view showing the external appearance of anEL display device of the present invention;

[0036]FIG. 7 shows the construction of an input terminal of the displaydevice;

[0037]FIG. 8 shows the construction of the input terminal of the displaydevice;

[0038]FIGS. 9A to 9C each show an example where a dryer agent isprovided in the pixel portion;

[0039]FIG. 10 is a cross-sectional view showing the constructions of thedriving circuit and the pixel portion of the display device;

[0040]FIG. 11 is a system block diagram of an electronic device in whichthe display device is built;

[0041]FIGS. 12A to 12E each show an example of the electronic device;

[0042]FIGS. 13A to 13D each show an example of the electronic device;

[0043]FIGS. 14A and 14B each show an embodiment mode of the presentinvention;

[0044]FIGS. 15A and 15B each show a CVD apparatus of the presentinvention;

[0045]FIGS. 16A to 16C each show an example of the embodiment mode ofthe present invention;

[0046]FIGS. 17A and 17B each show an example of the embodiment mode ofthe present invention;

[0047]FIGS. 18A to 18D each show an example of the embodiment mode ofthe present invention;

[0048]FIGS. 19A and 19B each show an example of the embodiment mode ofthe present invention;

[0049]FIGS. 20A and 20B each show an example of the embodiment mode ofthe present invention;

[0050]FIGS. 21A to 21C each show an example of the electronic devicethat uses a light-emitting device as its display unit;

[0051]FIG. 22 shows an example of the conventional technique; and

[0052]FIGS. 23A to 23E each show an example of the embodiment mode ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Embodiment modes and embodiments of the present invention aredescribed in detail below with reference to the drawings.

[0054] [Embodiment Mode 1]

[0055] Embodiment Mode 1 is described below with reference to FIGS. 1Ato 1D each showing a display device using a light-emitting element. FIG.1A shows a state where an element substrate 101, on which a drivingcircuit 108 and a pixel portion 109 are formed using TFTs (thin-filmtransistors) and a sealing substrate 102 are fixed using a sealingmember 105. A light-emitting element 103 is formed in the sealed spaceformed between the element substrate 101 and the sealing substrate 102.A dryer agent 106 is provided on the driving circuit or in the vicinityof the sealing member 105. It should be noted here that although notshown in this drawing, the dryer agent 106 may be contained in apartition wall 110 that is formed across the pixel portion 109 and thedriving circuit 108.

[0056] Each of the element substrate and sealing substrate is made of anorganic resin material, such as polyimide, polyethylene terephthalate(PET), polyethylene naphthalate (PEN), polyether sulfone (PES), oraramid. The thickness of each of these substrates is set at around 30 to120 μm to maintain the flexibilities of the substrates.

[0057] In the example shown in FIG. 1A, DLC films 107 are formed at endportions as gas barrier layers. Note that the DLC films are not formedon an external input terminal 104. An epoxy adhesive is used as thesealing member. To prevent from entering moisture, the DLC films 107 areformed to cover the sealing member 105 and the end portions of theelement substrate 101 and the sealing substrate 102.

[0058]FIG. 1B shows a construction where a DLC film 110 is formed tocover the undersurface of the element substrate 101, in addition to theDLC films 107 formed to cover the sealing member 105 and the endportions of the substrates 101 and 102. Although depending on thethickness, a DLC film has low permeability to light whose wavelength isshort (500 nm or less). Therefore, in this example, no DLC film isformed on the display surface (the main surface on a display side) ofthe sealing substrate 102. This construction, however, completelyprevents moisture from entering the element substrate 101 on which theTFTs are formed. As a result, the degradation of the TFTs and thelight-emitting element does not occur.

[0059]FIG. 1C shows a construction where gas barrier property isimproved. In this drawing, a DLC film is formed to cover whole surfacesof the element substrate 101, the sealing substrate 102, and the sealingmember 105, except for the external input terminal 104. In addition tothe improvement in gas barrier property, this construction has theeffect of preventing scratches or the like on the surfaces because thesurfaces of the plates are protected by the DLC film.

[0060]FIG. 1D shows an example where DLC films are formed on the elementsubstrate 113 and the sealing substrate 114 beforehand. Then, other DLCfilms are additionally formed to cover the end portions in which thesealing member for fixing these plates is formed.

[0061]FIG. 2 shows an example of a CVD apparatus used to form DLC films.This drawing mainly shows a vacuum chamber and other related processingmeans. As shown in this drawing, the vacuum chamber includes a commonchamber 202 that has a transporting means for transporting a targetsubstrate 218 to be processed, a load lock chamber 201 that inserts andremoves the target substrate, and a first reaction chamber 203 and asecond reaction chamber 204 that form DLC films on the target substrate.The load lock chamber 210 and the first and second reaction chambers 203and 204 are connected to the common chamber 202 via gate valves 205 to207. Also, these chambers 201 to 204 are provided with exhausting means208, 209, 211, and 214.

[0062] The first reaction chamber 203 is provided with a gas introducingmeans 212 and a discharge causing means 213. Similarly, the secondreaction chamber 204 is provided with a gas introducing means 215 and adischarge causing means 216. These gas introducing means introduceabove-described hydrocarbon gas or Ar, H₂ and the like into thechambers. Each discharge causing means is composed of a cathode and ananode, which are arranged in respective reaction chambers, and ahigh-frequency (1 to 120 MHz) power source. DLC films are formed bysetting the target substrate on the cathode side in the reactionchamber. Therefore, if DLC films are to be formed on both of the elementsubstrate and the sealing substrate, as shown in FIG. 1C, the posture ofthe target substrate need to be changed (for instance, the targetsubstrate is required to be turned around).

[0063]FIGS. 3A and 3B each show a state where a DLC film is formed onone surface of the target substrate in the first reaction chamber 203and another DLC film is formed on the other surface of the targetsubstrate in the second reaction chamber 204.

[0064] In FIG. 3A, a reaction chamber 301 is connected to a gasintroducing means 302 and includes a cathode 305, to which ahigh-frequency power source 304 is connected, and an anode 306 having ashower plate 309 for supplying gas to the reaction chamber. The reactionchamber 301 is also connected to an exhausting means 303. A targetsubstrate 308 is placed on the cathode 305. Pressure pins 307 are usedto transport the target substrate. With this construction, a DLC film isformed on one-surface and end portions of the target substrate in thereaction chamber. Also, if the cathode has a stepped cross section, asshown in FIG. 3A, it becomes possible to have the formed DLC film alsocover undersurface areas in the vicinity of the end portions of thetarget substrate. Needless to say, the DLC film covering theundersurface areas is thinner than that covering other areas.

[0065]FIG. 3B shows a example of construction of a reaction chamberwhere a DLC film is formed on a surface opposing to that processed inFIG. 3A (the undersurface of the target substrate). A reaction chamber310 is connected to a gas introducing means 312 and includes a cathode315, to which a high-frequency power source 314 is connected, and ananode 316 having a shower plate 320 for supplying gas to the reactionchamber 310. The reaction chamber 310 is also connected to an exhaustingmeans 313. A target substrate 318 is required to be set at the cathode315, so that the reaction chamber 310 is further provided with a holder319 and a mechanism 311 for moving the holder up or down. The targetsubstrate 318 is first held by pressure pins 317 and then is set at thecathode 315 by the holder 319 that is elevated by the mechanism 311. Inthis manner, a DLC film is formed on the surface opposing to thatprocessed in FIG. 3A (the undersurface of the target substrate).

[0066] As described above, with the plasma CVD apparatus shown in FIGS.2, 3A, and 3B, it becomes possible to realize the display devices shownin FIGS. 1A to 1D where DLC films are formed as gas barrier layers.Needless to say, FIGS. 2, 3A, and 3B each show an example constructionof the CVD apparatus, so that the display devices shown in FIGS. 1A to1D may be produced with a film forming apparatus having anotherconstruction. For instance, DLC films may be formed with a CVD apparatusthat utilizes a microwave or electron cyclotron resonance.

[0067] The DLC films used as gas barrier layers more effectively preventmoisture and oxygen from entering a sealed space and thus enhances thestability of a light-emitting element. For instance, this constructionreduces the number of dark spots resulting from the oxidation of acathode.

[0068] [Embodiment Mode 2]

[0069]FIGS. 14A and 14B each show an example where a pixel portion and adriving circuit are formed on a substrate having an insulating surface(such as a glass substrate, a ceramic substrate, a crystallized glasssubstrate, a metal substrate, or a plastic substrate).

[0070] In these drawings, reference numeral 1401 represents a gate-sidedriving circuit; numeral 1402, a source-side (data-side) drivingcircuit; and numeral 1403, a pixel portion. Signals transmitted to thegate-side driving circuit 1401 and the source-side driving circuit 1402are supplied from an FPC (flexible print circuit) 1405 via input wiring1404.

[0071] A sealing substrate 1406 is used to seal light-emitting elements.The light-emitting elements emit light toward the sealing substrate1406, so that the sealing substrate 1406 is required to havetransparency. Numeral 1407 represents a sealing resin used to seal thesealing substrate 1406 and the element substrate 1400. A cross-sectionalview taken along the line A-A′ in FIG. 14A is shown in FIG. 14B. In thisdrawing, the sealing substrate 1406 is also covered with a DLC film toprevent the penetration of oxygen.

[0072] After an insulating film 1411 is formed on the element substrate1400, a light-emitting element 1412 composed of a cathode 1413, anorganic compound layer (including a light-emitting layer) 1414, and ananode 1415 is formed on the insulating film 1411. A protecting layer1417 is further formed on the cathode 1413 to protect the light-emittingelement 1412 that is easily oxidized by oxygen and moisture. It ispreferable that the insulating film is transparent or translucent tovisible radiation.

[0073] The cathode 1413 and the anode 1415 are also transparent ortranslucent to visible radiation. Here, transparency to visibleradiation means that the permeability to visible radiation is around 80to 100% and translucency to visible radiation means that thepermeability to visible radiation is around 50 to 80%. The anode 1415and the cathode 1413 must be respectively made of a conductive oxidefilm with a work function of 4.5 to 5.5 and a conductive film with awork function of 2.0 to 3.5 (typically, a metal film including anelement belonging to Group 1 or 2 of the periodic table). In many cases,however, the metal coat is not transparent to visible radiation, so thatit is preferable that the construction shown in FIGS. 14A and 14B isused. The cathode 1413 that is translucent to visible radiation isformed by laminating a thin metal film with a thickness of 5 to 70 nm(preferably, 10 to 30 nm) and a conductive oxide film (ITO, forinstance). Note that the organic compound layer (including thelight-emitting layer) 1414 may adopt a well-known structure and theorganic compound layer may be used alone or laminated with a carrier(electrons or holes) injecting layer, a carrier transporting layer, or acarrier blocking layer.

[0074] To prevent the degradation of the light-emitting element due tooxygen and moisture, DLC films are formed at the end portions of thedisplay device and a dryer agent is further provided between the firstsubstrate 1400 and the second substrate 1406. Note that the dryer agentis provided by forming a barium oxide (BaO₂) layer on the secondsubstrate using an EB vapor deposition method or by sealing the dryeragent in a powder state between the substrates. Alternatively, the dryeragent may be provided to function as a spacer by mixing the dryer agentwith a resin and providing the mixture on partition walls or atpositions (such as on the driving circuit or wiring that connects thedriving circuit to picture elements) outside light-emitting areas.Further, the dryer agent may be mixed with a resin that is the materialof the partition walls. The dryer agent may be provided with any of themethods described above. Note that in this embodiment mode, powder ofbarium oxide is provided as the dryer agent in a space 1409 between asealing resin 1407 and a resin 1408, as shown in FIG. 14B.

[0075] With the construction shown in FIGS. 14A and 14B, emitted lightpasses through the cathode and is directly observed by an observer. Mostof the outside light is absorbed by an organic interlayer insulatingfilm 1419 made of a black resin, so that the amount of the outside lightreflected toward an observer is reduced to a level where no problemarises. As a result, the reflected light does not reach the observer andthe outside scenes are not reflected by the surface facing the observer.

[0076] The following is a description of the method of forming DLC filmsat end portions of the light-emitting device produced by laminating theelement substrate 1400 and the sealing substrate 1406, with reference toFIGS. 15A and 15B. A light-emitting device 1501 is held by a holdingmeans 1502 a in a reaction chamber 1500. The reaction chamber 1500 isprovided with an introducing opening 1508 and an exhausting opening 1509that respectively introduces and exhausts gas used to form DLC films.Also, means (RF electrodes) 1503 for causing plasma are provided in thereaction chamber 1500. The holding means 1502 a is fixed to the reactionchamber and the light-emitting device 1501 on the holding means 1502 ais pressed against the holding means 1502 a by the movable holding means1502 b.

[0077] The electrodes 1503 are connected to (high-frequency) powersources 1505 and matching circuits 1504. Typical RF power sources areused as the power sources 1505. The electrodes 1503 are connected to theRF power sources 1505 that apply voltages to the electrodes 1503. Aphase adjuster 1510 is provided to adjust the phases of the RF powersources 1505. With this construction, the electrodes are supplied withpower, whose phases differ from each other by 180°, from the RF powersources. FIG. 15A shows a state where one pair of electrodes is providedin the reaction chamber, however, a plurality of pairs of electrodes orcylindrical electrodes may be used.

[0078] To form DLC films in end portions of the light-emitting device1501, surfaces in the end portions need to be subjected to ionbombardment. Therefore, the holding means 1502 a is connected to a powersource 1507. To generate a self-bias, a capacitor 1511 is arrangedbetween the power source 1507 and the holding means 1502 a. The holdingmeans 1502 a is provided as a means for applying a bias to thesubstrate. Also, the holding means 1502 b is provided to prevent the DLCfilms from being formed on the entire surface of the light-emittingdevice 1501. That is, the holding means 1502 functions as a mask thatcovers a light-emitting area and the external input terminal (FPC) tothereby prevent the DCL films from forming thereon. Note that the layerforming conditions are appropriately set by an operator of the filmforming apparatus.

[0079] To form DLC films at end portions of the light-emitting deviceproduced by laminating an element substrate and a sealing substrate, theholding means 1502 a is divided into two masking portions: a maskingportion (hereinafter, a light-emitting area mask) that covers thelight-emitting area, and a masking portion (hereinafter, an externalinput terminal mask) that covers the external input terminal. Thesemasking portions are partially connected to each other. It is preferablethat the width of the connection between the light-emitting area maskand the external input terminal mask is set at 5 mm or less (see FIG.15B). It is also preferable that the relation between the width of theconnection and the height of the holding means 1502 b satisfies acondition “Height/Width≧around 2” (see FIG. 15B).

[0080] Aside from the holding means composed of the light-emitting areamask and the external input terminal mask, an ordinary masking tape maybe used in the CVD apparatus to cover the external input terminal tothereby prevent the formation of a DLC film thereon. To prevent thedegradation of the light-emitting element due to oxygen and moisture,DLC films need to be formed in four end portions of the light-emittingdevice 1501. To effectively and evenly form the DLC films, a member 1506supporting the holding means 1502 a may be given a rotating function.

[0081] The holding means 1502 a doubles as an electrode that applies anegative self-bias to the light-emitting device 1501. The power source1507 applies a negative self-bias to the electrode 1502. Minute DLCfilms are formed in the end surfaces of the light-emitting device 1501using a source gas accelerated by the negative self-bias voltage. Notethat the source gas is an unsaturated hydrocarbon gas (such as methane,ethane, propane, or butane), an aromatic gas (such as benzene ortoluene), or a halogenated hydrocarbon where at least one hydrocarbonmolecular is replaced by a halogen element, such as F, Cl, or Br.

[0082] In the manner described above, DLC films 1510 with a thickness of5 to 100 nm (preferably, 10 to 30 nm) are formed to coat the endportions of the light-emitting device. FIG. 23 shows a state where DLCfilms are formed on a light-emitting device using the film formingapparatus of the present invention. DLC films are directly formed on theside surfaces and edge portions of the surfaces of a substrate in thisembodiment mode. However, to bring the DLC films into intimate contact,nitride films (such as silicon nitride films or silicon oxynitridefilms) may be formed as base films before the DLC films are formed. Inthis case, the thickness of the nitride films is set at 2 to 20 nm.

[0083] [Embodiment 1]

[0084] The present invention is applicable to various types of displaydevices so long as the display devices use light-emitting elements. FIG.4 shows an example of display device to which the present invention isapplied. The display device in this drawing is an active matrix typedisplay device produced using TFTs. TFTs are classified into amorphoussilicon TFTs and polysilicon TFTs, depending on what materials are usedto produce semiconductor films that form channel formation regions. Thepresent invention is applicable to both types of TFTs.

[0085] It is impossible to produce an organic resin substrate, which isresistant to heat processing at 450° C. or higher, using a commerciallyavailable material. A laser anneal technique, however, makes it possibleto produce polysilicon TFTs only by heating the substrate to 300° C. orbelow. Also, in many cases, hydrogenation processing is required to beperformed during the production of polysilicon TFTs. A plasma-aidedhydrogenation processing makes it possible to produce polysilicon TFTsonly by heating the substrate to around 200° C.

[0086] In FIG. 4, an N-channel type TFT 452 and a P-channel type TFT 453are formed in a driving circuit portion 450, and a switching TFT 454 anda current control TFT 455 are formed in a pixel portion 451. These TFTsare formed using various components, such as island-like semiconductorlayers 403 to 406, a gate insulating film 407, and gate electrodes 408to 411.

[0087] A substrate 401 is made of an organic resin material (such aspolyimide, polyethylene terephthalate (PET), polyethylene naphthalate(PEN), polyether sulfone (PES), or aramid) to have a thickness of 30 to120 μm (typically. 75 μm). A blocking layer 402 is made of siliconoxynitride (SiO_(x)N_(y)) or a silicon nitride film to have a thicknessof 50 to 200 nm, thereby preventing the precipitation of oligomer or thelike from the substrate 401. An interlayer insulating film includes aninorganic insulating film 418 made of silicon nitride or siliconoxynitride and an organic insulating film 419 made of acrylic orpolyimide.

[0088] The driving circuit potion 450 includes a gate-signal-sidedriving circuit and a data-signal-side driving circuit having differentcircuit constructions, although the circuit constructions are notdescribed here. The N-channel type TFT 452 and the P-channel type TFT453 are connected to wirings 412 and 413 and are used to form a shiftresister, a latch circuit, and a buffer circuit.

[0089] In the pixel portion 451, data wiring 414 is connected to thesource of the switching TFT 454 and drain-side wiring 415 is connectedto the gate electrode 411 of the current control TFT 455. Also, thesource of the current control TFT 455 is connected to power sourcewiring 417 so as to connect a drain-side electrode 416 with the anode ofthe light-emitting element. FIGS. 5A and 5B each show a top view of thepixel portion constructed in this manner. For ease of explanation, thesame reference numerals as in FIG. 4 are used in FIGS. 5A and 5B. Also,a cross-sectional view taken along the line A-A′ in FIG. 5A is shown inFIG. 4.

[0090] As shown in FIG. 4, partition walls 420 and 421 are formed usingan organic resin, such as acrylic or polyimide, or preferably aphotosensitive organic resin to cover the wiring. The light-emittingelement 456 is composed of an anode 422 made of ITO (indium tin oxide),an organic compound layer 423 including a luminescent material, and acathode 424 made of MgAg, LiF, or the like. The partition walls 420 and421 are provided to cover the end portion of the anode 422, therebypreventing shorts between the cathode and the anode.

[0091] It does not matter whether the organic compound layer is made ofa low molecular material or a high molecular material. A vapordeposition method is used in the case of the low molecular material,while a spin coat method, a printing method, or an ink jet method isused in the case of the high molecular material.

[0092] A well-known high molecular material is a π-conjugated polymermaterial. The typical examples thereof are crystalline semiconductorfilm p-phenylene vinylene (PPV) derivatives, poly vinyl carbazole (PVK)derivatives, and polyfluorene derivatives. The organic compound layermade of such a material may be used alone or laminated with other layersto form a laminated structure, although a higher luminous efficiency isobtained in the latter case. Generally, the laminated structure isformed by stacking an anode, a hole injecting layer, a hole transportinglayer, a light-emitting layer, and an electron transporting layer inthis order. However, the laminated structure may be formed by stackingan anode, a hole transporting layer, a light-emitting layer, an electrontransporting layer or a hole injecting layer, a hole transporting layer,a light-emitting layer, an electron transporting layer, and an electroninjecting layer in this order. The present invention can be made withany of well-known laminated constructions. Also, the organic compoundlayer may be doped with a fluorescent coloring agent.

[0093] Typical materials are, for instance, disclosed in U.S. Pat. No.4,356,429, U.S. Pat. No. 4,539,507, U.S. Pat. No. 4,720,432, U.S. Pat.No. 4,769,292, U.S. Pat. No. 4,885,211, U.S. Pat. No. 4,950,950, U.S.Pat. No. 5,059,861, U.S. Pat. No. 5,047,687, U.S. Pat. No. 5,073,446,U.S. Pat. No. 5,059,862, U.S. Pat. No. 5,061,617, U.S. Pat. No.5,151,629, U.S. Pat. No. 5,294,869, U.S. Pat. No. 5,294,870, JapanesePatent Application Laid-open No. Hei 10-189525, Japanese PatentApplication Laid-open No. Hei 8-241048, and Japanese Patent ApplicationLaid-open No. Hei 8-78159.

[0094] It should be noted here that there are four major methods ofdisplaying color images. With the first method, three types oflight-emitting elements each corresponding to one of R (red), G (green),and B (blue) are formed. With the second method, a light-emittingelement that emits white light is combined with a color filter. With thethird method, a light-emitting element that emits blue or cyan light iscombined with a fluorescent member (a fluorescent color changing layer:CCM). With the fourth method, light-emitting elements each correspondingto one of R (red), G (green), and B (blue) are stacked using atransparent electrode as a cathode (an opposing electrode).

[0095] In more detail, an organic compound layer that emits red light ismade of cyanopolyphenylene, an organic compound layer that emits greenlight is made of polyphenylenevinylene, and an organic compound layerthat emits blue light is made of polyphenylenevinylene orpolyalkylphenylene. Each organic compound layer is 30 to 150 nm inthickness.

[0096] Organic EL materials that can be used as a light-emitting layerare given above, although the present invention is not limited to them.Any of available combinations of materials of a light-emitting layer, acharge transporting layer, and a charge injecting layer may be freelyselected. The organic compound layer in this embodiment has aconstruction where a light-emitting element is combined with a holeinjecting layer made of PEDOT (polythiophene) or PAni (polyaniline).

[0097] The cathode 424 placed on the organic compound layer 423 is madeof a material including magnesium (Mg), lithium (Li), or calcium (Ca)each having a low work function. It is preferable that an MgAg electrode(Mg: Ag=10:1) is used as the cathode 424. An MGAgAl electrode, LiAlelectrode, and LiFAl electrode may also be used as the cathode 424.

[0098] It is preferred to successively form the organic compound layer423 and the cathode 424 without leaving them in the air. This is becausethe condition of the interface between the cathode 424 and the organiccompound layer 423 greatly effects the luminous efficiency of thelight-emitting element. Note that in this specification, alight-emitting element means a light-emitting element composed of ananode (pixel electrode), an organic compound layer, and a cathode.

[0099] One laminated structure including the organic compound layer 423and the cathode 424 is required to be formed for each picture element,but the organic compound layer 423 is extremely vulnerable to moisture.Therefore, an ordinary photolithograph technique cannot be used to formthe laminated structure. Also, the cathode 424 made of an alkaline metalis easily oxidized. As a result, it is preferred to selectively form thelamination member with a vapor phase method, such as a vacuum depositionmethod, a sputtering method, or a plasma CVD method, using a physicalmask, such as a metal mask. Note that it is possible to selectively formthe organic compound layer with another method, such as an ink-jetmethod or a screen printing method, although it is currently impossibleto successively form cathodes with these methods. As a result, it ispreferable to use the vapor phase method.

[0100] Also, a protecting electrode for protecting the cathode 424 fromthe outside moisture and the like may be stacked on the cathode 424. Itis preferable that the protecting electrode is made of a low resistantmaterial including aluminum (Al), copper (Cu), or silver (Ag).Alternatively, the protecting electrode may be a transparent electrode.In this case, light is emitted in the direction of the arrow shown inFIG. 4 (the light emission in this direction is hereinafter referred toas a “top surface emission”, for ease of explanation). In this case, bymixing a black pigment into the organic resin interlayer insulating film419, no polarizing plate is required to form a black screen during anon-light-emission period. This protecting electrode is also expected toachieve a heat dissipation effect that lowers the temperature of theorganic compound layer. It is also effective to successively form theorganic compound layer 423, the cathode 424, and the protectingelectrode without leaving them in the air.

[0101] In FIG. 4, the switching TFT 454 has a multi-gate constructionand the current control TFT 455 is provided with an LDD overlapping thegate electrode. A TFT produced using a polysilicon operates at highspeed and therefore degradation, such as hot carrier injection, tends tooccur for the TFT. Therefore, TFTs are formed to have differentconstructions according to their functions and are provided in a pixelportion (in the case of FIG. 2, the switching TFT whose OFF current issufficiently reduced is combined with the current control TFT that isresistant to hot carrier injection), which is highly effective inproducing a display device that achieves high reliability and superiorimage display (high operation performance).

[0102]FIG. 6 shows the external appearance of such a display device. Thedirection in which an image is displayed depends on the construction ofthe light-emitting element, although light is emitted upward to displayimage in this drawing. In FIG. 6, an element substrate 601, on whichdriving circuit portions 604 and 605 and a pixel portion 603 have beenformed using TFTs, and a sealing substrate 602 are laminated using asealing member 610. One end of the element substrate 601 is providedwith an input terminal 608 via which an FPC is connected to the displaydevice. The input terminal 608 includes a plurality of terminals thatreceive an image data signal, various timing signals, and electricityfrom an external circuit. Here, the interval between the terminals isset at 500 μm. The input terminal 608 is connected to the drivingcircuit portion via wiring 609. Here, an IC ship 607 on which a CPU anda memory have been formed may be mounted on the element substrate 601using a COG (Chip on Glass) method or the like, as necessary.

[0103] A DLC film 611 is formed in end portions to prevent moisture andoxygen from entering through sealed portions and being degraded inlight-emitting elements. In the case where the element substrate 601 andthe sealing substrate 602 are made of an organic resin material, the DLCfilm may be formed to coat the entire surface of the display device,except for an input terminal, as described by referring to FIG. 1C. Inthis case, the input terminal is covered with a masking tape or a shadowmask prior to the formation of the DLC film.

[0104] As shown in FIG. 7, the input terminal is formed by stacking anITO 706 formed as an anode on wiring 705 made of titanium (Ti) andaluminum (Al). Incidentally, FIG. 8 is a cross-sectional view of theinput terminal taken along the line C-C′. An element substrate 701 and acover substrate 702 are laminated using a sealing member 703 and a DLCfilm 704 is formed to cover the sealing member 703 and the end portionsof the element substrate 701 and the cover substrate 702. In the drivingcircuit portion, an organic compound layer 707 and a cathode 708 areformed on a partition wall 709 and a contact region 710 is formed toestablish the contact between the cathode 708 and the wiring, as shownin FIG. 7.

[0105] By forming DLC films on a display device that uses an organicresin substrate, the degradation of light-emitting elements is preventedand the stability of the display device is ensured for the long term.The display device using the organic resin substrate is in particularsuitable as a display device for a portable device. If the portabledevice is used outdoors, however, it is required to increase thereliability of the display device in consideration of the exposure tothe direct sunlight, wind, and rain. The DLC films also satisfy thisrequirement for increasing the reliability of the display device.

[0106] [Embodiment 2]

[0107] In this embodiment, the degradation of a light-emitting elementis prevented using a means for sealing a dryer agent, such as bariumoxide, in gaps of a light-emitting device or a space in which thelight-emitting element is sealed. In FIGS. 1A to 1D, a dryer agent isprovided on a driving circuit or in areas in which a sealing member hasbeen formed. In the present embodiment, a dryer agent is provided in adifferent manner, as shown in FIGS. 9A to 9C. As can be seen from thesedrawings, a dryer agent is arranged in partition walls that are providedto separate adjacent picture elements in a pixel portion. FIGS. 9A to 9Care each a cross-sectional view taken along the line B-B′ in FIG. 5. Forease of explanation, the same reference numerals as in FIGS. 4, 5A, and5B are used in FIGS. 9A to 9C.

[0108]FIG. 9A shows an example where a dryer agent 480 is dispersed inthe partition wall 421. The partition wall 421 is made of athermosetting or photosensitive organic resin material. The dryer agentis dispersed in the organic resin material prior to the polymerizationof the organic resin material, and then the organic resin materialincluding the dryer agent is applied as it is to form the partition wall421.

[0109]FIG. 9B shows an example where a dryer agent 481 is formed on anorganic resin insulating film 419. In this case, the dryer agent isformed at a predetermined position to have a predetermined pattern usinga vacuum deposition method or a printing method. Then, the partitionwall 421 is formed on the dryer agent 481.

[0110]FIG. 9C shows an example where a dryer agent 482 is formed on thepartition wall 421. In this case, the dryer agent 482 is formed using avacuum deposition method or a printing method, similarly to the caseshown in FIG. 9B.

[0111]FIGS. 9A to 9C show examples of the formation of the dryer agent,and these examples may be combined with each other as appropriate. Also,the constructions of the present embodiment may be combined with theconstruction shown in FIG. 1. If the stated formations of the dryeragent are applied to the display device of Embodiment 1, a displaydevice with high reliability is realized by the dryer agent combinedwith the gas barrier property of the DLC films.

[0112] [Embodiment 3]

[0113]FIG. 10 shows an example of a display device that uses an invertedstagger type TFT. A substrate 501 and a light-emitting element 556 usedin this embodiment are the same as those of Embodiment 1 and thereforeare not described here.

[0114] The inverted stagger type TFT is formed by stacking the substrate501, gate electrodes 508 to 511, gate insulating films 507, andsemiconductor films 503 to 506 in this order. In FIG. 10, an N-channeltype TFT 552 and a P-channel type TFT 553 are formed in a drivingcircuit portion 550. Also, a switching TFT 554, a current control TFT555, and a light-emitting element 556 are formed in a pixel portion 551.An interlayer insulating film is composed of an inorganic insulatingfilm 518 made of silicon nitride or silicon oxynitride and an organicresin film 519 made of acrylic or polyimide.

[0115] The driving circuit portion 550 includes a gate-signal-sidedriving circuit and a data-signal-side driving circuit having differentcircuit constructions, although the circuit constructions are notdescribed here. The N-channel type TFT 552 and the P-channel type TFT553 are connected to wiring 512 and 513 and form a shift resister, alatch circuit, and a buffer circuit.

[0116] In the pixel portion 551, data wiring 514 is connected to thesource side of the switching TFT 554 and drain-side wiring 515 isconnected to a gate electrode 511 of the current control TFT 555. Also,the source of the current control TFT 555 is connected to a powersupplying wiring 517 so as to connect a drain-side electrode 516 to ananode of the light-emitting element.

[0117] Partition walls 520 and 521 are formed using an organic resin,such as acrylic or polyimide, or preferably a photosensitive organicresin to cover the wiring. The light-emitting element 556 is composed ofan anode 522 made of ITO (indium tin oxide), an organic compound layer523 produced using an organic EL material, and a cathode 524 made ofMgAg, LiF, or the like. The partition walls 520 and 521 are provided tocover the end portion of the anode 522, thereby preventing shortsbetween the cathode and the anode.

[0118] Components other than the TFTs, such as the pixel portion, of thedisplay device have the same constructions as in Embodiment 1. It isadvantageous to use the inverted stagger type TFT produced usingpolysilicon because the manufacturing line for amorphous silicon TFTs(usually formed as inverted stagger type TFTs) can be used as it is.Needless to say, a laser anneal technique using an eximer laser makes itpossible to produce polysilicon TFTs at a processing temperature of 300°C. or below.

[0119] [Embodiment 4]

[0120] In this embodiment, an example of construction of an electronicdevice using the display device of Embodiment 1 is described withreference to FIG. 11. A display device 900 in FIG. 11 includes a pixelportion 921, which is composed of picture elements 920 formed by TFTs ona substrate, and a data-signal-side driving circuit 915 and agate-signal-side driving circuit 914 that are used to drive the pixelportion. In the example shown in FIG. 11, the data-signal-side drivingcircuit 915 uses a digital driving method and includes a shift register916, latch circuits 917 and 918, and a buffer circuit 919. Also, thegate-signal-side driving circuit 914 includes various components, suchas a shift register and a buffer (not shown).

[0121] In the case of VGA, the pixel portion 921 includes 640 pictureelements wide by 480 picture elements high. Also, as described byreferring to FIGS. 4, 5A, and 5B, a switching TFT and a current controlTFT are arranged for each picture element. The light-emitting elementoperates as follows. When gate wiring is selected, the gate of theswitching TFT opens, data signal on source wiring is accumulated in acapacitor, and the gate of the current control TFT opens. That is, datasignal inputted from the source wiring causes the flow of current intothe current control TFT and the light-emitting element emits light.

[0122] The system block diagram shown in FIG. 11 relates to theapplication of the display device of Embodiment 1 to a portableinformation terminal, such as a PDA. The display device of Embodiment 1includes a pixel portion 921, a gate-signal-side driving circuit 914,and a data-signal-side driving circuit 915.

[0123] An external circuit connected to the display device includes apower circuit 901 composed of a stabilized power source and a high-speedand high-precision operational amplifier, an external interface port 902provided with a USB terminal or the like, a CPU 903, an input meanscomposed of a pen input tablet 910 and detection circuit 911, a clocksignal oscillator 912, and a control circuit 913.

[0124] The CPU 903 includes an image signal processing circuit 904 and atablet interface 905 for receiving signals from the pen input tablet910, and is connected to a VRAM 906, a DRAM 907, a flash memory 908, anda memory card 909. Information processed in the CPU 903 is sent as animage signal (data signal) from the image signal processing circuit 904to the control circuit 913. The control circuit 913 has a function ofconverting the image signal and a clock signal to signals which can beused corresponding to the data-signal-side driving circuit 915 and thegate-signal-side driving circuit 914, respectively.

[0125] In more detail, the control circuit 913 has a function ofdividing the image signal into a plurality of pieces of datacorresponding to respective picture elements. The control circuit 913also has a function of converting a horizontal synchronizing signal anda vertical synchronizing signal inputted from the outside into twosignals: a start signal used by the driving circuit, and a timingcontrol signal required to convert the current generated by an internalpower circuit into an alternating current.

[0126] It is desired that a portable information terminal, such as aPDA, can be used outdoors (in a train, for instance) for a long timeusing a rechargeable battery as a power supply (that is, withoutconnecting the terminal to an AC outlet). Such an electronic device isalso required to be easily portable and thus the weight and size thereofneed to be reduced. The battery occupying the majority of weight of theelectronic device increases in weight in accordance with the increase inbattery capacity. Accordingly, various measures based on softwaretechniques need to be used to reduce the power consumption of theelectronic device. For instance, the time period in which a backlight isturned on is controlled or a standby mode is used.

[0127] In the case of the electronic device of the present embodiment,if no input signal is inputted from the pen input tablet 910 into thetablet interface 905 of the CPU 903 for a predetermined time period, theelectronic device is placed in a standby mode and the componentsenclosed with dotted lines in FIG. 11 stop their operations insynchronization with each other. Also, the display device reduces thestrength of light emitted by the light-emitting element or stops theimage displaying operation. Alternatively, memories corresponding torespective picture elements may be used to change the electronic deviceinto a still image displaying mode. With these measures, the powerconsumption of the electronic device is reduced.

[0128] Also, a still image may be displayed by stopping the operationsof the image signal processing circuit 904 of the CPU 903 and the VRAM906 to reduce the power consumption. In FIG. 11, the components thatcontinue to operate even in the still image displaying mode areindicated using dotted lines. Also, as shown in FIG. 6, the controlcircuit 913 may be mounted on the element substrate using an IC chipwith a COG method, or integrally formed in the display device.

[0129] The display device using the organic resin substrate of thepresent invention contributes to the weight reduction of an electronicdevice. If a display device whose size is five inches or the like isused for an electronic device, the weight of the electronic devicebecomes around 60 g with a glass substrate. However, with a displaydevice using the organic resin substrate of the present invention, theweight of the electronic device is reduced to 10 g or less. Further,because DLC films coat the surface of the display device, the surfaceincreases in hardness and becomes resistant to scratches or the like. Asa result, the beautiful condition of the display screen is continued. Asdescribed above, the present invention achieves a superior effect for anelectronic device, such as a portable information terminal.

[0130] [Embodiment 5]

[0131] In this embodiment, a method of forming a cathode of alight-emitting element is described with reference to FIGS. 16A to 16C.In these drawings, an insulating film 1601, an anode 1602 formed as afirst electrode, an organic compound layer 1603, a cathode 1604 formedas a second electrode, and a DLC film 1605 are stacked in this order.

[0132] First, the description is given of FIG. 16A below. In thisdrawing, a silicon oxide film is used as the insulating film 1601, aconductive oxide film (thickness=120 nm) formed by adding gallium oxideto zinc oxide is used as the anode 1602, and a lamination film composedof copper-phthalocyanine (a hole injecting layer) with a thickness of 20nm and Alq₃ (quinolilato-aluminum complex: light-emitting layer) with athickness of 50 nm is used as the organic compound layer 1603. Thecathode 1604 has a laminated construction where a transparent electrode1604 b is stacked on a translucent electrode 1604 a formed using anultra-thin metal film. For instance, the translucent electrode 1604 a isformed using an MgAg film with a thickness of 20 nm (alloy film formedby evaporating magnesium and silver) and the transparent electrode 1604b is formed using a conductive oxide film (thickness=200 nm) formed byadding gallium oxide to zinc oxide. A protecting film 1605 is formedusing a DLC film.

[0133] Also, in FIG. 16B, the insulating film 1601, the anode 1602, theorganic compound layer 1603, and an electron injecting layer 1606 thatis a LiF film are stacked in this order. The cathode 1604 that is aconductive oxide film (thickness=200 nm) formed by adding gallium oxideto zinc oxide and a protecting film 1605 formed using a DLC film arestacked on the electron injecting layer 1606.

[0134] In FIG. 16C, the insulating film 1601, the anode 1602, and theorganic compound layer 1603 are stacked in this order. Then an LiF film1606 is stacked on the organic compound layer 1603 as an electroninjecting layer, and the cathode 1604 is stacked on the film 1606. Thecathode 1604 is composed of the translucent electrode 1604 a that is anMgAg film with a thickness of 50 nm or less (preferably, 20 nm) (alloyfilm formed by evaporating magnesium and silver) and the transparentelectrode 1604 b that is a conductive oxide film (thickness=200 nm)formed by adding gallium oxide to zinc oxide. The protecting film 1605that is formed using a DLC film is stacked on the cathode 1604.

[0135] After a light-emitting element is formed to have any one of theconstructions described above, the light-emitting element is sealed andDLC films are formed at end portions with any one of the aforementionedmethods. In this manner, the degradation due to oxygen and moisture isprevented.

[0136] [Embodiment 6]

[0137] In this embodiment, the cathode of a light-emitting element isformed with a method differing from that of Embodiment 1. Here, themethod of forming a cathode is below described with reference to FIGS.17A and 17B. In FIG. 17A, a cathode 1702 made of an alkaline metal (Lior Mg, for instance) with a low work function is formed on an insulatingfilm 1701. Then, an organic compound layer 1703, an anode 1704, and aprotecting layer 1705 (a DLC film) are formed on the cathode 1702.

[0138] In FIG. 17B, a transparent electrode 1702 a that is a transparentconductive film ITO and a translucent electrode 1702 b that is anultra-thin (thickness=50 nm or less) metal film (Al—Li alloy film orMgAg alloy film, for instance) are stacked in this order on theinsulating film 1701 to form the cathode 1702. Then, the organiccompound layer 1703, the anode 1704, and the protecting film 1705 thatis a DLC film are formed on the cathode 1702.

[0139] [Embodiment 7]

[0140] In this embodiment, the organic compound layer is described inmore detail. Accordingly, it is possible to combine the presentembodiment with any construction of the embodiment modes and Embodiments1 to 6. Note that in this embodiment, an anode 1801 that is a firstelectrode is formed using a conductive oxide film. Also, a cathode thatis a second electrode is formed using a conductive film to have any ofconstructions described with reference to FIGS. 18A to 18D.

[0141]FIG. 18A shows a construction where an anode 1801, a holeinjecting layer 1802, a hole transporting layer 1803, a light-emittinglayer 1804, an electron transporting layer 1805, an electron injectinglayer 1806, and a cathode 1807 are formed and stacked in this order.FIG. 18B shows a construction where the anode 1801, the hole injectinglayer 1802, the light-emitting layer 1804, the electron transportinglayer 1805, the electron injecting layer 1806, and the cathode 1807 areformed and stacked in this order. FIG. 18C shows a construction wherethe anode 1801, the hole injecting layer 1802, the light-emitting layer1804, the electron injecting layer 1806, and the cathode 1807 are formedand stacked in this order. FIG. 18D shows a construction where the anode1801, the hole injecting layer 1802, the hole transporting layer 1803,the light-emitting layer 1804, and the cathode 1807 are formed andstacked in this order.

[0142] These are just a few examples of the construction of the organiccompound layer and therefore there are various different constructionsthat can be used for the present invention. It is possible to use thestated constructions of the organic compound layer in combination withEmbodiments 1 to 6.

[0143] [Embodiment 8]

[0144] In this embodiment, in addition to DLC films formed at endportions of a light-emitting device, a dryer agent is provided in alight-emitting element to prevent the degradation due to oxygen andmoisture. This construction is described with reference to FIGS. 19A and19B. Reference numeral 1901 represents a glass substrate that is a firstsubstrate, and a base insulating film 1902 is formed on the firstsubstrate 1901. An amorphous silicon layer is formed on the baseinsulating film 1902 and is crystallized using a well-known technique toproduce a crystalline silicon film, then the crystalline silicon film isprocessed to have an island-like pattern, thereby forming an activelayer 1904 of each TFT.

[0145] A gate insulating film (not shown), gate electrodes 1905,interlayer insulating films 1906, and pixel electrodes (firstelectrodes) 1907 made of an alkaline metal or an alkaline earth metalwith a low work function are formed on the active layer. An organiccompound layer 1908 is formed on the pixel electrodes 1907, and an anode(second electrode) 1909 is formed on the organic compound layer 1908using a conductive oxide film (ITO film, in this embodiment) made of acompound of an indium oxide and a tin oxide.

[0146] A partition wall 1910 is formed under the organic compound layerto cover each TFT. Here, if the partition wall is made of a materialproduced by mixing a dryer agent with a resin, moisture existing underthe protecting layer 1911 is absorbed by the partition wall and thedegradation of the light-emitting element is prevented.

[0147]FIG. 19B shows another example where a resin (hereinafter, a dryeragent) 1912 mixed with a dryer agent is provided on the protective layer1911 in the area of a driving circuit. This dryer agent 1912 alsofunctions as a spacer. Note that the arrangement positions of the dryeragent 1912 may be freely determined so long as the agent is not arrangedon input wiring or in areas in which pixel electrodes emit light. Also,the dryer agent 1912 may be provided by combining the stated arrangementmethods. Further, the present embodiment may be combined with any of theconstructions described in Embodiments 1 to 7.

[0148] [Embodiment 9]

[0149] In this embodiment, a first substrate (such as a glass substrate)2001 is laminated with a third substrate (a film-like substrate, such asa plastic film or an ultra-thin stainless substrate) 2004 on which alight-emitting element is to be formed. After the formation of thelight-emitting element, the third substrate 2004 is laminated with asecond substrate 2003. Then the glass substrate 2001 is peeled off usinga laser or an agent and a film-like substrate is instead laminated. Thisprocessing is described in detail below with reference to FIGS. 20A and20B.

[0150] After the light-emitting element formed on the third substrate2004 is sealed with the second substrate 2003, a laser light is appliedonto the undersurface of the glass substrate 2001 to evaporate a bondinglayer 2002 (such as polyimide, polyamide, polyimideamide, an urethaneresin, a photo-curing resin, a thermosetting resin, a polychlorinatedvinyl resin, an epoxy resin, an acrylic adhesive, and a gum adhesive).In this manner, the glass substrate 2001 is peeled off. In thisembodiment, a linear beam is formed using the second harmonic(wavelength=532 nm) of a YAG laser and is irradiated onto the bondinglayer 2002 through the glass substrate 2001. As a result, the bondinglayer 2002 is evaporated and the glass substrate 2001 is peeled off.

[0151] After this, a plastic film substrate or a thin metal substrate islaminated instead of the peeled glass substrate. This realizes aflexible light-emitting device whose weight and thickness are bothreduced. Note that it does not matter whether the bonding layer 2002 islaminated with the first substrate 2001 and then the third substrate2004 or is laminated with the third substrate 2004 and then the firstsubstrate 2001. The present embodiment may be combined with any of theembodiment modes and Embodiments 1 to 8.

[0152] [Embodiment 10]

[0153] In this embodiment, an organic compound layer is produced bycombining an organic compound (hereinafter, a singlet compound) thatemits light by a singlet exciton (singlet) and an organic compound(hereinafter, a triplet compound) that emits light by a triplet exciton(triplet). Here, the singlet compound means a compound that emits lightonly via a singlet excited state and the triplet compound means acompound that emits light via a triplet excited state.

[0154] Typical organic compounds that can be used as the tripletcompound are described in the following theses.

[0155] (1) T. Tsutsui, C. Adachi, S. Saito, Photochemical Processes inOrganized Molecular Systems, ed. K. Honda, (Elsevier Sci. Pub., Tokyo,1991) p.437

[0156] (2) M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley,M. E. Thompson, S. R. Rorrest, Nature 395 (1998) p.151

[0157] *This thesis discloses an organic compound expressed by thefollowing formula.

[0158] (3) M. A. Baldo, S. Lamansky, P. E. Burrrows, M. E. Thompson, S.R. Forrest. Appl. Phys. Lett., 75 (1999) p.4

[0159] (4) T. Tsutsui, M.-J. Yang, M. Yahiro, K. Nalamura, T. Watanabe,T. Tsuji, Y. Fukuda. T. Wakimoto, S. Mayaguchi, Jpn. Appl. Phys., 38(12B) (1999) L1502

[0160] In addition to the luminescent materials described in the abovetheses, it is thought that luminescent materials (in more detail, metalcomplexes and organic compounds) expressed by the following molecularformulas may also be used.

[0161] (Formula 1)

[0162] (“Et” indicates ethyl group. “M” indicates an element belongingto VIII-X groups in periodic table.)

[0163] (Formula 2)

[0164] (“M” indicates an element belonging to VIII-X groups in periodictable.)

[0165] In the above molecular formulas, M is an element belonging toGroup 8, 9, or 10 of the periodic table. In the above theses, platinumand iridium are used. However, the inventors of the present inventionconsider that it is preferable to use nickel, cobalt, or palladiumbecause these materials are inexpensive compared with platinum andiridium and therefore suitable for reducing the cost of fabricatinglight-emitting devices. It is thought that nickel is in particularpreferable because nickel complexes are easy to form and thus theproductivity is increased.

[0166] The triplet compound has a higher luminous efficiency than thesinglet compound and it is possible to reduce an operating voltage(voltage required to have a light-emitting element emit light) withoutreducing the amount of emitted light and brightness. This embodiment ismade using this feature.

[0167] If a low-molecular organic compound is used as a light-emittinglayer, the life span of a light-emitting layer that emits red light isshorter than those of light-emitting layers that emit other coloredlights under present circumstances. This is because the luminousefficiency of the red-light-emitting layer is lower than those of theother-colored-light-emitting layers and the operating voltage thereof isrequired to be increased to obtain the same brightness as those of theother-colored-light-emitting layers. This promotes the degradation ofthe red-light-emitting layer.

[0168] In this embodiment, however, a triplet compound having a highluminous efficiency is used as the red-light-emitting layer, so that theoperating voltage thereof does not be required to be increased to obtainthe same brightness as those of the light-emitting layers that emitgreen and blue lights. Accordingly, a situation is avoided where thedegradation of the red-light-emitting-element is extremely accelerated.As a result, it becomes possible to display color images without causingproblems, such as color deviations. The reduced operating voltage isalso preferable because it becomes unnecessary for transistors to havehigh withstand voltages.

[0169] It should be noted here that the triplet compound is used as thelight-emitting layer that emits red light in this embodiment, althoughthe triplet compound may also be used as the light-emitting layer thatemits green light or the light-emitting layer that emits blue light.

[0170] In the case of RGB color display, three types of light-emittingelements that respectively emit red light, green light, and blue lightneed to be provided in a pixel portion. In this case, it is possible touse the triplet compound for the light-emitting element that emits redlight and use the singlet compound for other light-emitting elements.

[0171] By selectively using the triplet compound and the singletcompound in this manner, it becomes possible to have each light-emittingelement operate at the same operating voltage (10V or less, preferably 3to 10V). Accordingly, all power sources for the light-emitting devicecan have the same voltage (3V or 5V), which allows circuit design to becarried out without difficulty. Note that the construction described inthis embodiment may be combined with any of the constructions ofEmbodiments 1 to 6.

[0172] [Embodiment 11]

[0173] A light-emitting device formed by implementing the presentinvention can be incorporated to various electric-equipment, and a pixelportion is used as an image display portion. Given as such electronicequipment of the present invention are cellular phones, PDAs, electronicbooks, video cameras, notebook computers, and image play back deviceswith the recording medium, for example, DVD (digital versatile disc),digital cameras, and the like. Specific examples of those are shown inFIGS. 12A to 13D.

[0174]FIG. 12A shows a cellular phone, which is composed of a displaypanel 9001, an operation panel 9002, and a connecting portion 9003. Thedisplay panel 9001 is provided with a display device 9004, an audiooutput portion 9005, an antenna 9009, etc. The operation panel 9002 isprovided with operation keys 9006, a power supply switch 9002, an audioinput portion 9008, etc. The present invention is applicable to thedisplay device 9004.

[0175]FIG. 12B also shows a cellular phone, which is composed of a mainbody or a housing 9101, a display device 9102, an audio output portion9103, an audio input portion 9104, and an antenna 9105. The displaydevice 9102 can be provided with a touch sensor so as to operate buttonson the display. By using the organic resin substrate of the presentinvention, the substrate can be bent after the completion of the displaydevice. Therefore, while such characteristics are used, the housing with3 dimensional curing surfaces, which is designed based on the humanengineering can be employed by the display device without difficulty.

[0176]FIG. 12C shows a mobile computer, or a portable informationterminal, which is composed of a main body 9201, a camera portion 9202,an image receiving portion 9203, operation switches 9204, and a displaydevice 9205. The present invention can be applied to the display device9205. In such electronic devices, the display device of 3 to 5 inches isemployed, however, by employing the display device of the presentinvention, the reduction of the weight in the portable informationterminal can be attained.

[0177]FIG. 12D shows a portable book, which is composed of a main body9301, display devices 9303, and a recording medium 9304, an operationswitch 9305, and an antenna 9306, and which displays the data recordedin MD or DVD and the data received by the antenna. The present inventioncan be applied to the display devices 9302. In the portable book, thedisplay device of the 4 to 12 inches is employed. However, by employingthe display device of the present invention, the reduction of the weightand thickness in the portable book can be attained.

[0178]FIG. 12E shows a video camera, which is composed of a main body9401, a display device 9402, an audio input portion 9403, operationswitches 9404, a battery 9405, and the like. The present invention canbe applied to the display device 9402.

[0179]FIG. 13A shows a personal computer, which is composed of a mainbody 9601, an image input portion 9602, a display device 9603, and a keyboard 9604. The present invention can be applied to the display device9601.

[0180]FIG. 13B shows a player employing a recording medium with programsrecorded thereon (hereinafter referred to as recording medium), which iscomposed of a main body 9701, a display device 9702, a speaker portion9703, a recording medium 9704, and an operation switch 9705. The deviceemploys DVD (digital versatile disc), CD, etc. as the recording mediumso that music can be listened, movies can be seen and games and internetcan be done. The present invention can be applied to the display device9702.

[0181]FIG. 13C shows a digital camera, which is composed of a main body9801, a display device 9802, an eyepiece portion 9803, an operationswitch 9804, and an image receiving portion (not shown). The presentinvention can be applied to the display device 9802.

[0182]FIG. 13D also shows a digital camera, which is composed of a mainbody 9901, a display device 9902, an image receiving portion 9903, anoperation switch 9904, a battery 9905, etc. The present invention can beapplied to the display device 9902. By using the organic resin substrateof the present invention, the substrate can be bent after the completionof the display device. Therefore, while such characteristics are used,the housing with 3 dimensional curing surfaces, which is designed basedon the human engineering can be employed by the display device withoutdifficulty.

[0183] The display device of the present invention is employed in thecellular phones in FIGS. 12A and 12B, the mobile computer or theportable information terminal in FIG. 12C, the portable book in FIG.12D, and the personal computer in FIG. 13A. The display device canreduce the power consumption of the above device by displaying whiteletters on the black display in a standby mode.

[0184] In the operation of the cellular phones shown in FIGS. 12A and12B, luminance is lowered when the operation keys are used, and theluminance is raised after usage of the operation switch, whereby the lowpower consumption can be realized. Further, the luminance of the displaydevice is raised at the receipt of a call, and the luminance is loweredduring a call, whereby the low power consumption can be realized.Besides, in the case where the cellular phone is continuously used, thecellular phone is provided with a function of turning off a display bytime control without resetting, whereby the low power consumption can berealized. Note that the above operations may be conducted by manualcontrol.

[0185]FIGS. 21A and 21B show cellular phones. Reference numeral 2701denotes a display panel, and reference numeral 2702 denotes an operationpanel. The display panel 2701 and the operation panel 2702 are connectedin the connection portion 2703. The cellular phone has a display portion2704, an audio output portion 2705, operation keys 2706, a power supplyswitch 2707, and an audio input portion 2708. The present invention canbe applied to the display portion 2704. FIGS. 21A and 21B show thelengthwise cellular phone and the widthwise cellular phone,respectively.

[0186]FIG. 21C shows a car audio system, which is composed of a mainbody 2801, a display portion 2802, and operation switches 2803 and 2804.The light-emitting device of the present invention can be applied to thedisplay portion 2802. In this embodiment the car audio system for beingmounted in a car is shown. However, it can be applied to the standstillcar audio. The display portion 2804 can reduce the power consumption bydisplaying white letters in the black display.

[0187] Further, it is effective to incorporate an optical sensor and toprovide a function of modulating emission luminance in accordance withbrightness in a usage environment by providing means for detecting thebrightness in the usage environment. A user can recognize image orcharacter information without problems if brightness of 100 to 150 incontrast ratio in comparison with the brightness of the usageenvironment is secured. That is, it is possible that the luminance of animage is raised in the bright usage environment to make the image easyto see while the luminance of an image is suppressed in the dark usageenvironment to thereby suppress the power consumption.

[0188] Although it is not shown here, the present invention can beapplied to the display device which is employed in a navigation system,a refrigerator, a washing machine, a micro-wave oven, a telephone, a faxmachine, etc. As described above, the applicable range of the presentinvention is so wide that the present invention can be applied tovarious products.

[0189] According to the present invention described above, in a displaydevice that uses an organic resin substrate, DLC films are formed on theouter surfaces of a sealing member and an outer surface or end portionsof the organic resin substrate. This construction improves the gasbarrier property of the display device and prevents the degradation oflight-emitting elements. Also, if a DLC film is formed on a lightincident surface, ultraviolet rays are blocked, the light chemicalreaction of the organic resin substrate is suppressed, and thedegradation of the organic resin substrate is prevented.

[0190] Such a display device realizes an electronic device whose weightis reduced and shock resistance is improved. Also, the surface on whicha DLC film has been formed is hardened, so that the surface of anorganic resin substrate becomes resistant to flaws. As a result, ahigh-quality display screen is achieved and remains clear for a longtime.

[0191] By forming a DLC film to cover end portions of substrates, fromentering oxygen and moisture through between the substrates isprevented. This achieves the prolonged life spans of light-emittingelements and a light-emitting device. Also, by providing a DLC film tocover the entire surface except for an area in which light emission isperformed, it becomes unnecessary to strictly control the formation ofthe DLC film. Further, by forming an interlayer insulating film using ablack resin, the reflection of light by the first substrate isprevented. As a result, a problem in that outside scenes, such as theface of an observer, is reflected by a light-emitting device is solvedwithout using an expensive circular polarizing film.

What is claimed is:
 1. A light-emitting device comprising: alight-emitting element including a first electrode, a second electrode,and an organic compound layer sandwiched between said first electrodeand said second electrode; and a DLC film formed in edge portions andside portions of said light-emitting device.
 2. A light-emitting devicecomprising a light-emitting element including a first electrode, asecond electrode, and an organic compound layer sandwiched between saidfirst electrode and said second electrode, wherein said light-emittingelement is formed on a first substrate having an insulating surface andis laminated with a second substrate using a sealing member, wherein aDLC film is successively formed in side portions of said firstsubstrate, exposed portions of the sealing member, and side portions ofsaid second substrate.
 3. A light-emitting device comprising: alight-emitting element including a first electrode, a second electrodeand an organic compound layer sandwiched between said first electrodeand said second electrode, wherein said light-emitting element is formedon a first substrate having an insulating surface and is laminated witha second substrate using a sealing member, wherein a DLC film issuccessively formed in side portions of said first substrate, exposedportions of said sealing member, and side portions of said secondsubstrate, and wherein nitride films are provided between said DLC filmand said first substrate and between said DLC film and said secondsubstrate.
 4. The light-emitting device according to claim 3, whereinsaid nitride films are one of silicon nitride films and siliconoxynitride films.
 5. The light-emitting device according to claim 3,wherein a thickness of each nitride film is in a range of 2 nm to 20 nm.6. The light-emitting device according to any one of claims 1 to 3,wherein a thickness of said DLC film is in a range of 5 nm to 10 nm. 7.The light-emitting device according to any one of claims 2 and 3,wherein said first substrate is a glass substrate and said secondsubstrate is permeable to light emitted from said organic compoundlayer.
 8. The light-emitting device according to any one of claims 1 and3, wherein said light-emitting device comprise a partition wall thatcovers an end portion of said first electrode and is made of a resininto which a dryer agent is mixed.
 9. The light-emitting deviceaccording any one of claims 1 to 3, wherein said light-emitting devicecomprises a partition wall that covers an end portion of the firstelectrode, wherein a dryer agent mixed into a resin is provided on saidpartition wall.
 10. The light-emitting device according any one ofclaims 1 to 3, wherein said light-emitting device is incorporated intoan electric equipment selected from the group consisting of a cellularphone, a mobile computer, a portable book, a video camera, a personalcomputer, a player, a digital camera and a car audio system.
 11. Adisplay device comprising: a pair of substrates that are each flexibleand made of an organic resin material; a light-emitting element providedbetween said pair of substrates; and a sealing member provided betweenend portions of said pair of substrates, wherein a coating film whosemain ingredient is carbon is formed in end portions of the pair ofsubstrates and on outer surfaces of the sealing member.
 12. A displaydevice comprising: a pair of substrates that are each flexible and madeof an organic resin material; a light-emitting element provided betweenthe pair of substrates; and a sealing member provided between endportions of the pair of substrates so as to fix the pair of substrates,wherein a coating film whose main ingredient is carbon is formed on oneof said pair of substrates, in end portions of said pair of substrates,on outer portion of one of said pair of substrate, and on outer surfacesof said sealing member.
 13. A display device comprising: a pair ofsubstrates that are each flexible and made of an organic resin material;a light-emitting element provided between said pair of substrates; and asealing member provided between end portions of said pair of substrates,wherein a coating film whose main ingredient is carbon is formed inouter portions of said pair of substrates, and on outer surfaces of saidsealing member.
 14. A display device comprising: a first substrate thatis flexible and made of an organic resin material; a light-emittingelement formed over said first substrate; a second substrate that isflexible, made of an organic resin material, and provided to oppose thelight-emitting element; and a sealing member provided to fix said firstsubstrate and said second substrate, wherein a coating film whose mainingredient is carbon is formed in end portions of said first substrateand said second substrate and on outer surfaces of said sealing member.15. A display device comprising: a first substrate that is flexible andmade of an organic resin material; a light-emitting element formed oversaid first substrate; a second substrate that is flexible, made of anorganic resin material, and provided to oppose said light-emittingelement; and a sealing member provided to fix said first substrate andsaid second substrate, wherein a coating film whose main ingredient iscarbon is formed in end portions of said first substrate and said secondsubstrate, on outer surface of said first substrate and on outersurfaces of said sealing member.
 16. A display device comprising: afirst substrate that is flexible and made of an organic resin material;a light-emitting element formed over said first substrate; a secondsubstrate that is flexible, made of an organic resin material, andprovided to oppose said light-emitting element; and a sealing memberprovided to fix said first substrate and said second substrate, whereina coating film whose main ingredient is carbon is formed on outersurfaces of said first substrate and said second substrate and on outersurfaces of said sealing member.
 17. A display device comprising: afirst substrate that is flexible and made of an organic resin material;a pixel portion that is formed over said first substrate using a TFT anda light-emitting element; a second substrate that is flexible, made ofan organic resin material, and provided to oppose said light-emittingelement; and a sealing member provided to fix said first substrate andsaid second substrate, wherein a coating film whose main ingredient iscarbon is formed in outer regions of said first substrate and saidsecond substrate and on outer surfaces of said sealing member.
 18. Adisplay device comprising: a first substrate that is flexible and madeof an organic resin material; a pixel portion that is formed over saidfirst substrate using a TFT and a light-emitting element; a secondsubstrate that is flexible, made of an organic resin material, andprovided to oppose said light-emitting element; and a sealing memberprovided to fix said first substrate and said second substrate, whereina coating film whose main ingredient is carbon is formed in outerregions of said first substrate and said second substrate, on outersurface of said first substrate, and on outer surfaces of said sealingmember.
 19. A display device comprising: a first substrate that isflexible and made of an organic resin material; a pixel portion that isformed over said first substrate using a TFT and a light-emittingelement; a second substrate that is flexible, made of an organic resinmaterial, and provided to oppose said light-emitting element; and asealing member provided to fix said first substrate and said secondsubstrate, wherein a coating film whose main ingredient is carbon isformed on outer surfaces of said first substrate and said secondsubstrate and on outer surfaces of said sealing member.
 20. A displaydevice according to any one of claims 11 to 19, wherein carbon atoms arebonded into an SP³ bond in said coating film.
 21. A display deviceaccording to any one of claims 11 to 19, wherein said coating film has ahardness of 15 to 25 GPa.
 22. A display device according to any one ofclaims 11 to 19, wherein said coating film is a DLC film.
 23. A displaydevice according to any one of claims 14 to 19, wherein said secondsubstrate is permeable to luminescence light emitted from thelight-emitting element.
 24. A display device according to any one ofclaims 11 to 19, wherein said light-emitting element includes a compoundthat emits light via a triplet excited state.
 25. A display deviceaccording to any one of claims 11 to 19, wherein said display device isincorporated into an electric equipment selected from the groupconsisting of a cellular phone, a mobile computer, a portable book, avideo camera, a personal computer, a player, a digital camera and a caraudio system.